Communication control device, communication control method, terminal device, and program

ABSTRACT

There is provided a communication control device including a decision unit configured to decide radio resources available for inter-device communication within a cell, and a notification unit configured to notify a terminal device located within the cell of the radio resources. When the radio resources are modified, the notification unit gives notification of modification of the radio resources through paging. When the radio resources are modified, the radio resources before the modification refrain from being used for the inter-device communication after a predetermined timing and the radio resources after the modification are used for the inter-device communication after the predetermined timing.

TECHNICAL FIELD

The present disclosure relates to a communication control device, acommunication control method, a terminal device, and a program.

BACKGROUND ART

Near field inter-terminal communication or device-to-devicecommunication (D2D communication) is a communication form in which asignal is directly transmitted between terminal devices, unlike acommunication form in which a signal passes through a base station incellular communication. Therefore, in the D2D communication, new useforms of terminal devices unlike the existing cellular communication areexpected to appear. For example, various applications such asinformation sharing by data communication between near terminal devicesor a group of near terminal devices, information distribution frominstalled terminal devices, and autonomous communication between devicescalled Machine Type Communication (MTC) can be considered.

With regard to the significant increase in data traffic with the recentincrease of smartphones, the D2D communication can also be considered tobe utilized in off-loading of data. For example, when terminal devicesare in a state suitable for the D2D communication such as a case inwhich a distance between terminal devices is small, resource consumptionand process loads in a Radio Access Network (RAN) can be suppressed byoff-loading moving image data in the D2D communication. Thus, the D2Dcommunication is useful for both communication providers and users.Therefore, at present, the D2D communication is recognized and noticedas one of the important technical areas necessary for Long TermEvolution (LTE) of the 3rd Generation Partnership Project (3GPP)standardization commission as well.

For example, as a technology related to D2D communication according tothe same communication scheme as a communication scheme of cellularcommunication, a technology for Peer-to-Peer (P2P) communication betweenuser equipments (UEs) according to Time Division-Code Division MultipleAccess (TD-CDMA) is disclosed in Patent Literature 1.

CITATION LIST Patent Literature

-   Patent Literature 1: JP 2007-512755T

SUMMARY OF INVENTION Technical Problem

According to the technology of Patent Literature 1, radio resources canbe allocated to the UEs. However, when the resources allocated to theUEs are modified, it is not clear how the UEs recognize the modificationof the resources. For example, according to the technology of PatentLiterature 1, the UEs are assumed to be in connection states in a cell.Therefore, when the UEs are in an idle mode, the UEs are not guaranteedto recognize the modification of the radio resources. As a result, theUEs may perform D2D communication using radio resources not admitted inthe D2D communication. Further, even when the UEs recognize and use theallocated radio resources, there is a possibility of the partner UEs ofthe UEs in the D2D communication not recognizing and using the radioresources. As a result, an error may occur in the D2D communicationbetween the UEs.

It is desirable to provide a terminal device in an idle state ofcellular communication with a structure in which an error ininter-device communication can be suppressed using radio resourcesadmitted in the inter-device communication.

Solution to Problem

According to an embodiment of the present disclosure, there is provideda communication control device including a decision unit configured todecide radio resources available for inter-device communication within acell, and a notification unit configured to notify a terminal devicelocated within the cell of the radio resources. When the radio resourcesare modified, the notification unit gives notification of modificationof the radio resources through paging. When the radio resources aremodified, the radio resources before the modification refrain from beingused for the inter-device communication after a predetermined timing andthe radio resources after the modification are used for the inter-devicecommunication after the predetermined timing.

According to another embodiment of the present disclosure, there isprovided a communication control method including deciding radioresources available for inter-device communication within a cell,notifying a terminal device located within the cell of the radioresources, and when the radio resources are modified, givingnotification of modification of the radio resources through paging. Whenthe radio resources are modified, the radio resources before themodification refrain from being used for the inter-device communicationafter a predetermined timing and the radio resources after themodification are used for the inter-device communication after thepredetermined timing.

According to another embodiment of the present disclosure, there isprovided a terminal device including a resource recognition unitconfigured to recognize radio resources available for inter-devicecommunication within a cell when the radio resources are decided andnotification thereof is given, a control unit configured to control theinter-device communication in a manner that the recognized radioresources are used for the inter-device communication, and amodification recognition unit configured to recognize modification ofthe radio resources when the radio resources are modified andnotification of the modification of the radio resources is given throughpaging. When the radio resources are modified, the control unit controlsthe inter-device communication in a manner that the radio resourcesbefore the modification refrain from being used for the inter-devicecommunication after a predetermined timing and the radio resources afterthe modification are used for the inter-device communication after thepredetermined timing.

According to another embodiment of the present disclosure, there isprovided a program causing a computer to function as a resourcerecognition unit configured to recognize radio resources available forinter-device communication within a cell when the radio resources aredecided and notification thereof is given, a control unit configured tocontrol the inter-device communication in a manner that the recognizedradio resources are used for the inter-device communication, and amodification recognition unit configured to recognize modification ofthe radio resources when the radio resources are modified andnotification of the modification of the radio resources is given throughpaging. When the radio resources are modified, the control unit controlsthe inter-device communication in a manner that the radio resourcesbefore the modification refrain from being used for the inter-devicecommunication after a predetermined timing and the radio resources afterthe modification are used for the inter-device communication after thepredetermined timing.

Advantageous Effects of Invention

According to one or more embodiments of the present disclosure describedabove, it is possible to suppress an error in the inter-devicecommunication using radio resources admitted in the inter-devicecommunication in the terminal device in the idle mode of cellularcommunication.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram illustrating TDD configurations.

FIG. 2 is an explanatory diagram illustrating an example of a pagingoccasion of each terminal device.

FIG. 3 is an explanatory diagram illustrating an example of a subframeof the paging occasion.

FIG. 4 is an explanatory diagram illustrating an example of informationincluded in a paging message.

FIG. 5 is an explanatory diagram illustrating an example of an operationof the terminal device in regard to paging.

FIG. 6 is an explanatory diagram illustrating an example of a radioframe in which a PRACH is located.

FIG. 7 is an explanatory diagram illustrating an example of a subframein which the PRACH is located.

FIG. 8 is an explanatory diagram illustrating an example of informationblocks included in system information.

FIG. 9 is an explanatory diagram illustrating a timing of notificationof modification of the system information and a timing of themodification of the system information.

FIG. 10 is an explanatory diagram illustrating an example of a schematicconfiguration of a radio communication system 1 according to anembodiment.

FIG. 11 is a block diagram illustrating an example of the configurationof a base station according to the embodiment.

FIG. 12 is an explanatory diagram illustrating an example of radioresources (radio resources for paging in regard to terminal devices 200performing D2D communication) not admitted as D2D resources.

FIG. 13 is an explanatory diagram illustrating an example of radioresources (radio resources of the PRACH) not admitted as the D2Dresources.

FIG. 14 is an explanatory diagram illustrating an example of the decidedD2D resources.

FIG. 15 is an explanatory diagram illustrating an example of informationincluded in the paging message according to the embodiment.

FIG. 16 is a block diagram illustrating an example of the configurationof the terminal device according to the embodiment.

FIG. 17 is an explanatory diagram illustrating an example of anoperation of the terminal device in regard to paging according to theembodiment.

FIG. 18 is a flowchart illustrating an example of a schematic flow of acommunication control process on a base station side according to theembodiment.

FIG. 19 is a flowchart illustrating an example of a schematic flow of aD2D resource modification determination process according to theembodiment.

FIG. 20 is a flowchart illustrating an example of a schematic flow of acommunication control process on the base station side according to theembodiment.

FIG. 21 is an explanatory diagram illustrating an example ofinterference between groups of D2D communication.

FIG. 22 is an explanatory diagram illustrating an example of the D2Dresources decided for each group of the D2D communication.

FIG. 23 is a flowchart illustrating an example of a schematic flow of acommunication control process on a base station side according to amodification example of the embodiment.

FIG. 24 is a block diagram illustrating a first example of a schematicconfiguration of an eNB to which the technology of the presentdisclosure may be applied.

FIG. 25 is a block diagram illustrating a second example of a schematicconfiguration of an eNB to which the technology of the presentdisclosure may be applied.

FIG. 26 is a block diagram illustrating an example of a schematicconfiguration of a smartphone to which technology according of thepresent disclosure may be applied.

FIG. 27 is a block diagram illustrating an example of a schematicconfiguration of a car navigation device to which technology accordingto the present disclosure may be applied.

DESCRIPTION OF EMBODIMENTS

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the appended drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

The description will be made in the following order.

1. Radio communication technology in 3GPP

2. Schematic configuration of radio communication system

3. Configuration of base station

4. Configuration of terminal device

5. Flow of process

6. Modification example

6.1. Overview

6.2. Configuration of base station

6.3. Flow of process

7. Application examples

7.1. Application example of base station

7.2. Application example of terminal device

8. Conclusion

1. Radio Communication Technology in 3GPP

First, a technology for radio communication in 3GPP will be describedwith reference to FIGS. 1 to 9.

(TDD)

In LTE, Frequency Division Duplex (FDD) or Time Division Duplexing (TDD)is adopted as a duplex communication scheme. In FDD, different frequencybands are used for downlink transmission and uplink transmission. InTDD, the same frequency band is used for downlink transmission anduplink transmission, but the downlink transmission and the uplinktransmission are performed at different times.

For example, in LTE, 10 subframes are included in each radio frame of 10ms. Further, 7 TDD configurations #0 to #6 are decided as configurationsof the radio frame in the TDD. Hereinafter, a specific example of thispoint will be described with reference to FIG. 1.

FIG. 1 is an explanatory diagram illustrating the TDD configurations. InFIG. 1, 7 TDD configurations, that is, configurations 0 to 6, areillustrated. As described above, the radio frame includes 10 subframes.Each subframe is set to one of a downlink subframe (D), an uplinksubframe (U), and a special subframe (S). The special subframe is asubframe that is inserted between the downlink subframe and the uplinksubframe in order to ensure a time for switching between downlink anduplink.

The TDD configuration is transmitted in system information. Morespecifically, the TDD configuration is transmitted in System InformationBlock Type 1 (SIB 1).

(Paging)

Paging Occasion

A paging occasion in LTE will be described with reference to FIGS. 2 and3.

In LTE, the paging occasion is decided. More specifically, a systemframe number (SFN) of the radio frame for performing paging and asubframe for performing the paging are decided.

The SFN of the radio frame for performing the paging in regard to eachterminal device (that is, UE) is decided according to the followingexpression.SFN mod T=(T/N)(UE_ID mod N)  [Math 1]

UE_ID is 10 low-order bits of an International Mobile SubscriberIdentity (IMSI) of the terminal device (that is, the UE). T is a pagingperiod. In other words, T is a Discontinuous Reception (DRX) cycle. N isa smaller value between T and nB. That is, N=Min(T, nB) is satisfied. Tand nB are transmitted in System Information Block Type 2 (SIB 2) of thesystem information.

T and nB are selected from the following values.T={32,64,128,256}  [Math 2]nB={4T,2T,T,T/4,T/8,T/16,T/32}  [Math 3]

As described above, the radio frame for performing the paging is decidedin regard to each terminal device. Hereinafter, a specific example ofthe paging occasion of each terminal device will be described withreference to FIG. 2.

FIG. 2 is an explanatory diagram illustrating an example of a pagingoccasion of each terminal device. The paging occasion of each terminaldevice (terminal devices A and B) is illustrated in FIG. 2. Thus, forexample, in each paging period, the paging occasion is present for eachterminal device (terminal devices A and B). For example, when anotherterminal device is added, a paging occasion can be newly added.

In LTE, a subframe for performing the paging is decided according to thevalue of a parameter Ns. For example, for both of TDD and FDD, the valueof Ns is one of 1, 2, and 3.

For example, for TDD, the paging can be performed in subframe #0 whenNs=1. The paging can be performed in subframe #0 and subframe #5 whenNs=2. The paging can be performed in subframe #0, subframe #5, andsubframe #6 when Ns=3. Hereinafter, this point will be describedspecifically with reference to FIG. 3.

FIG. 3 is an explanatory diagram illustrating an example of a subframeof the paging occasion. TDD configuration 0 is illustrated in FIG. 3.For example, when Ns=2, the paging occasion is thus present in subframe#0 and subframe #5 which are the downlink subframes.

In FDD, the paging can be performed in subframe #9 when Ns=1. The pagingcan be performed in subframe #4 and subframe #9 when Ns=2. The pagingcan be performed in subframe #0, subframe #4, subframe #5, and subframe#9 when Ns=3.

As described above, when Ns=2 and Ns=3, the paging can be performed inthe plurality of subframes. The subframes in which the paging isperformed in each UE are decided depending on UE_ID of each UE.

As described above, the subframes in which the paging is performed ineach terminal device are decided.

Paging Message

Next, specific content of a paging message will be described withreference to FIG. 4.

FIG. 4 is an explanatory diagram illustrating an example of informationincluded in a paging message. Referring to FIG. 4, the paging messageincludes, for example, a paging record list, a flag of systeminformation modification, and a flag of an earthquake and tsunamiwarning system (ETWS) indication.

The paging records are lists of a maximum of 16 call records. The pagingrecord list includes a UE identity of the terminal device (that is, theUE) to be called. The UE identity in the paging record list is anSAE-Temporary Mobile Subscriber Identity (S-TMSI) or an InternationalMobile Subscriber Identity (IMSI). The paging record list includesinformation regarding a core network domain of a paging source. Theinformation indicates whether the core network domain of the pagingsource is a circuit switched (CS) domain or a packet switched (PS)domain.

The flag of the system information modification indicates whether thesystem information is modified. For example, when the system informationis modified, the flag is 1. When the system information is not modified,the flag is 0. Basically, the flag of the system informationmodification is 1 when any system information is modified. However, theflag of the system information modification is not 1 (that is, remainsto be 0) when only exceptional information of a part of the systeminformation is modified. The exceptional information includes, forexample, information regarding the ETWS and information regarding acommercial mobile alert system (CMAS).

The flag of the ETWS indication indicates whether an indication of anearthquake and tsunami warning system is given.

Operation of Terminal Device in Regard to Paging

Next, an operation of the terminal device in regard to the paging willbe described with reference to FIG. 5.

FIG. 5 is an explanatory diagram illustrating an example of theoperation of the terminal device in regard to the paging. Referring toFIG. 5, the terminal device in the idle mode first monitors whether aPaging Radio Network Temporary Identifier (P-RNTI) is present in aPhysical Downlink Control CHannel (PDCCH) in the subframe of apredetermined paging occasion.

When a P-RNTI is present in the PDCCH in the subframe of the pagingoccasion, the paging message is included in the subframe. Accordingly,the terminal device acquires the paging message. As described above, thepaging message includes the paging record list, the flag of the systeminformation modification, and the flag of the ETWS indication. When noP-RNTI is present in the PDCCH, the terminal device monitors the PDCCHin a subsequent paging occasion again.

The terminal device (that is, the UE) checks whether the UE identitydestined for the self-device is present in the paging record list whenthe terminal device acquires the paging message. When the UE identitydestined for the self-device is present in the paging record list, theterminal device recognizes that the terminal device is called from anetwork. In this case, the terminal device checks, from the informationregarding the core network domain, whether the call source is the CSdomain or the PS domain. Conversely, when the UE identity destined forthe self-device is not present in the paging record list, the terminaldevice monitors the PDCCH in a subsequent paging occasion again.

The terminal device also checks, from the flag of the system informationmodification, whether the system information is modified when theterminal device acquires the paging message. When the system informationis modified, the terminal device acquires the system information again.

The terminal device checks, from the flag of the ETWS indication,whether the ETWS indication is present when the terminal device acquiresthe paging message. When the ETWS indication is given, the terminaldevice performs a predetermined operation including an emergency alarmoperation.

(Random Access)

Next, a timing of random access will be described with reference toFIGS. 6 and 7.

The terminal device transmits a PRACH preamble with a Physical RandomAccess CHannel (PRACH) in a random access procedure for transition fromthe idle mode of radio resource control (RRC) to a connection mode ofthe RRC (RRC connected mode). In LTE, a transmission timing (that is, atiming of the PRACH) of the PRACH preamble is designated in advance by aPRACH configuration index.

First, the PRACH configuration index designates a radio frame (that is,a radio frame with which the PRACH preamble can be transmitted) in whichthe PRACH is located. Specifically, according to the PRACH configurationindex, the PRACH is located in each radio frame, radio frames in whichthe SFN is even, or radio frames in which the SFN is odd. Thus, thePRACH is present at intervals of 10 ms or intervals of 20 ms.Hereinafter, a specific example of this point will be described withreference to FIG. 6.

FIG. 6 is an explanatory diagram illustrating an example of a radioframe in which a PRACH is located. A timing of the radio frame withwhich the PRACH is transmitted is illustrated as the timing of the PRACHin FIG. 6. For example, when the PRACH configuration index is 0, thePRACH is located in the radio frames in which the SFN is even. That is,the PRACH is present at intervals of 20 ms. As illustrated in FIG. 6,for example, when the paging period is 320 ms (that is, 32 radioframes), the PRACH is located in 16 radio frames during one pagingperiod.

As another specific example, for example, when the PRACH configurationindex is 55, the PRACH is located in each radio frame.

Second, the PRACH configuration index designates the subframe (that is,the subframe with which the PRACH preamble can be transmitted) in whichthe PRACH is located. For example, any one of preamble formats 0 to 4corresponds to the PRACH configuration index. For example, in preambleformats 0 to 3, the PRACH configuration index designates a combinationof the subframes with which the PRACH preamble can be transmitted. Inpreamble format 4 of TDD, the PRACH configuration index designates anuplink pilot time slot (UpPTS) in the special subframe as a timing atwhich the PRACH preamble can be transmitted. Hereinafter, a specificexample of the subframe in which the PRACH is located will be describedwith reference to FIG. 7.

FIG. 7 is an explanatory diagram illustrating an example of the subframein which the PRACH is located. TDD configuration 0 is illustrated inFIG. 7. For example, when the TDD configuration is configuration 0 andthe PRACH configuration index is 0, the PRACH is located in subframe #2in the radio frame. That is, the PRACH preamble can be transmitted withsubframe #2.

As still another specific example, for example, when the PRACHconfiguration index is 55, the preamble format is the preamble format 4and the PRACH is located in the UpPTS in the special subframe. That is,the PRACH preamble can be transmitted with the UpPTS.

For example, even when the terminal device performs MTC, the terminaldevice is assumed to attempt to perform connection to a base station atany timing in a request of an operation system, application software, orthe like. That is, the terminal device performing the MTC is assumed totransmit the PRACH preamble.

(System Information)

Content of System Information

The system information includes various kinds of information regardingradio communication in a cell. For example, the system information inLTE includes a master information block (MIB) and various systeminformation blocks (SIBs). Hereinafter, a specific example of this pointwill be described with reference to FIG. 8.

FIG. 8 is an explanatory diagram illustrating an example of theinformation blocks included in the system information. In FIG. 8, oneMIB and the plurality of SIBs are illustrated as the system information.As a specific example, SIB 1 of the plurality of SIBs includes, forexample, information regarding the TDD configuration. SIB 2 of theplurality of SIBs includes a paging period (or DRX cycle) T and aparameter nB for deciding the paging occasion of each terminal device,and a PRACH configuration index for deciding a timing of random access.SIB 2 further includes a modification period coefficient for deciding amodification timing of the system information.

The MIB and the various SIBs are transmitted at respective periods. TheMIB is transmitted on a Physical Broadcast CHannel (PBCH) arranged at afixed position in a frequency direction and a time direction. SIB 1 istransmitted with the radio resources designated by the MIB and locatedat a position in the frequency direction and the time direction. Theremaining SIBs are transmitted with the radio resources designated bySIB 1.

Modification of System Information

When the system information is modified, the system information ismodified at a pre-decided timing. Specifically, the system informationcan be modified at each system information modification period. Thesystem information modification period is obtained by multiplying theDRX cycle (that is, the paging period T) by the modification periodcoefficient included in SIB 2. When the system information is modified,notification of the modification of the system information is givenbefore the system information after the modification is transmitted.Hereinafter, specific content of a timing of the notification of themodification of the system information and a timing of the modificationof the system information will be described with reference to FIG. 9.

FIG. 9 is an explanatory diagram illustrating the timing of thenotification of the modification of the system information and thetiming of the modification of the system information. In FIG. 9, twomodification periods (N) and a system modification period (N+1) areillustrated for the system information. For example, when the systeminformation is modified, the notification of the modification of thesystem information is given through paging during the modificationperiod (N). During the modification period (N), the system informationbefore the modification is transmitted. After the notification of themodification of the system information is given during the modificationperiod (N), the system information after the modification is transmittedby the base station during the modification period (N+1). Then, as soonas the modification period (N+1) starts, the terminal device acquiresthe information block after the modification at a timing at which eachinformation block of the system information is transmitted. The terminaldevice uses the system information before the modification until theterminal device acquires the system information after the modification.

2. Schematic Configuration of Radio Communication System

Next, a schematic configuration of a radio communication system 1according to the embodiment of the present disclosure will be describedwith reference to FIG. 10. FIG. 10 is an explanatory diagramillustrating an example of a schematic configuration of the radiocommunication system 1 according to the embodiment. Referring to FIG.10, the radio communication system 1 includes a base station 100 and twoor more terminal devices 200. The radio communication system 1 adopts,for example, LTE as a communication scheme of cellular communication.For example, TDD is adopted in the radio communication system 1.

(Base Station 100)

The base station 100 performs radio communication with the terminaldevices 200 located within a cell 10. That is, the base station 100transmits user data or control information to the terminal devices 100in a downlink manner and receives user data or control information fromthe terminal devices 200 in an uplink manner.

For example, the base station 100 transmits the system information. Morespecifically, for example, the base station 100 transmits the MIB on thePBCH. The base station 100 transmits SIB 1 with the radio resourcesdesignated by the MIB and transmits the remaining SIBs with the radioresources designated by SIB 1. For example, as described above, SIB 1includes the information regarding the TDD configuration. SIB 2 includesthe paging period (or DRX cycle) T and the parameter nB for deciding thepaging occasion of each terminal device 200, and the PRACH configurationindex for deciding a timing of random access. SIB 2 further includes themodification period coefficient for deciding a modification timing ofthe system information.

For example, the base station 100 performs the paging. Morespecifically, for example, the base station 100 performs the paging tothe UE at a timing according to each UE at the paging period. The basestation 100 notifies the terminal device 200 of presence or absence ofthe call to the terminal device, presence or absence of the modificationof the system information, or the like through paging.

For example, the base station 100 performs the procedure of the randomaccess with the terminal device 100. More specifically, for example, thebase station 100 receives the PRACH preamble from the terminal device200 with the PRACH.

In particular, in the embodiment, the base station 100 decides the radioresources available for the D2D communication within the cell 10. Then,the base station 100 notifies the terminal devices 200 of the radioresources.

(Terminal Device 200)

The terminal device 200 performs the radio communication with the basestation 100 when the terminal device 200 is located within the cell 10formed by the base station 100. That is, the terminal device 200receives the user data or the control information from the base station100 in the downlink manner and transmits the user data or the controlinformation to the base station 100 in the uplink manner.

For example, the terminal device 200 receives the system informationtransmitted by the base station 100 to acquire the system information.

Specifically, for example, the terminal device 200 acquires SIB 1. Then,the terminal device 200 recognizes the TDD configuration from SIB 1.Then, the terminal device 200 receives downlink data and transmitsuplink data according to the TDD configuration.

For example, the terminal device 200 acquires SIB 2. Then, the terminaldevice 200 recognizes the paging period (or the DRX cycle) T and theparameter nB from SIB 2. Then, the terminal device 200 specifies thesubframe which is the paging occasion of the self-device from the pagingperiod T and the parameter nB and receives a paging message with thesubframe.

For example, the terminal device 200 recognizes the timing of the PRACHfrom SIB 2. Then, the terminal device 200 transmits the PRACH preambleon the PRACH when the idle mode of the radio resource control (RRC)transitions to the connection mode of the RRC.

In particular, in the embodiment, the terminal device 200 performs theD2D communication with another terminal device 200. For example, theterminal device 200 performs the D2D communication using the radioresources, the notification of which is given by the base station 100.Referring back to FIG. 10, for example, the terminal devices 200A and200B perform the D2D communication. For example, the D2D communicationis performed according to Orthogonal Frequency-Division Multiplexing(OFDM).

The example of the configuration of the radio communication system 1according to the embodiment of the present disclosure has been describedabove with reference to FIG. 10. In the embodiment, by allowing theterminal device 200 in the idle mode of the cellular communication touse the radio resources admitted in the D2D communication, it ispossible to suppress an error in inter-device communication.Hereinafter, the specific content will be described in <<2.Configuration of base station>>, <<4. Configuration of terminaldevice>>, <<5. Flow of process>>, and <<6. Modification example>>.

3. Configuration of Base Station

Next, an example of the configuration of the base station 100 accordingto the embodiment will be described with reference to FIGS. 11 to 15.FIG. 11 is a block diagram illustrating an example of the configurationof the base station 100 according to the embodiment. Referring to FIG.11, the base station 100 includes an antenna unit 110, a radiocommunication unit 120, a network communication unit 130, a storage unit140, and a control unit 150.

(Antenna Unit 110)

The antenna unit 110 receives a radio signal and outputs the receivedradio signal to the radio communication unit 120. The antenna unit 110transmits a transmission signal output by the radio communication unit120.

(Radio Communication Unit 120)

The radio communication unit 120 performs the radio communication withthe terminal devices 200 located within the cell 10.

(Network Communication Unit 130)

The network communication unit 130 communicates with other communicationnodes. For example, the network communication unit 130 communicates withanother base station 100, a Mobility Management Entity (MME), and thelike.

(Storage Unit 140)

The storage unit 140 stores a program and data used for an operation ofthe base station 100.

(Control Unit 15)

The control unit 150 supplies various functions of the base station 100.The control unit 150 includes a D2D resource decision unit 151, a D2Dresource notification unit 153, and a D2D resource modificationnotification unit 155.

(D2D Resource Decision Unit 151)

The D2D resource decision unit 151 decides the radio resources availablefor the D2D communication within the cell 10.

For example, the D2D resource decision unit 151 decides the radioresources (hereinafter, “D2D resources”) available for the D2Dcommunication within the cell 10 based on information regarding specificradio resources used by the terminal devices 200 in the idle mode in theradio resource control. More specifically, for example, the D2D resourcedecision unit 151 decides any radio resources excluding the specificradio resources as the D2D resources. Hereinafter, a specific example ofthe specific radio resources will be described.

First Example of Specific Radio Resources to be Excluded: RadioResources for Paging

As a first example, the specific radio resources include radio resourcesfor paging. That is, the D2D resources are radio resources excluding theradio resources for paging.

For example, the radio resources for paging are radio resources used forthe paging on all of the terminal devices 200 located within the cell10. For example, as illustrated in FIG. 3 described above, when theparameter Ns used to decide the subframe for performing the paging is 2,the paging in regard to any of the terminal devices 200 can be performedin subframe #0 and subframe #5. Accordingly, the D2D resource decisionunit 151 decides the radio resources of one of the subframes excludingsubframe #0 and subframe #5 as the D2D resources.

Thus, the radio resources for paging are not decided as the D2Dresources, and thus the terminal devices 200 do not perform the D2Dcommunication using the radio resources for paging. As a result, theterminal devices 200 can be prevented from not receiving the pagingmessage due to the D2D communication.

As another example, the radio resources for paging may be the radioresources used for the paging in regard to the terminal devices 200performing the D2D communication within the cell 10. That is, the D2Dresource decision unit 151 may decide any radio resources excluding theradio resources used for the paging in regard to the terminal devices200 performing the D2D communication as the D2D resources.

In this case, for example, the base station 100 first recognizes theterminal devices 200 performing the D2D communication. For example, theterminal devices 200 performing the D2D communication notify the basestation 100 of the D2D communication when the terminal devices 200perform the D2D communication, and the D2D resource decision unit 151recognizes the terminal devices 200 performing the D2D communication.Then, the D2D resource decision unit 151 calculates the paging occasionin regard to each terminal device 200 performing the D2D communication.The D2D resource decision unit 151 may decide any radio resourcesexcluding the radio resources of the paging occasion as the D2Dresources. Hereinafter, a specific example of this point will bedescribed with reference to FIG. 12.

FIG. 12 is an explanatory diagram illustrating an example of radioresources (the radio resources for paging in regard to the terminaldevices 200 performing D2D communication) not admitted as the D2Dresources. In FIG. 12, the paging occasions of the terminal devices 200Aand 200B performing the D2D communication illustrated in FIG. 10 areillustrated in the time direction. Thus, for example, when only theterminal devices 200A and 200B perform the D2D communication in the cell10, the D2D resource decision unit 151 decides any radio resourcesexcluding the radio resources of the paging occasions as the D2Dresources. Specifically, for example, the radio resources of the radioframe excluding a certain radio frame can be decided as the D2Dresources.

Thus, when only the radio resources for paging in regard to the terminaldevices 200 actually performing the D2D communication are excluded froma target of the D2D resources rather than all of the radio resources forpaging, more radio resources can be admitted as the D2D resources. As aresult, off-loading in regard to more traffic can be realized. That is,it is possible to suppress consumption of the radio resources andprocessing loads in an RAN.

Second Example of Specific Radio Resources to be Excluded: RadioResources for Random Access

As a second example, the specific radio resources include radioresources used in the random access procedure for transition to theconnection mode of the radio resource control. That is, the D2Dresources are resources excluding the radio resources used in the randomaccess procedure.

For example, the radio resources used in the random access procedure areradio resources of the Physical Random Access CHannel (PRACH). That is,the D2D resources are radio resources other than the radio resources ofthe PRACH. Hereinafter, a specific example of this point will bedescribed with reference to FIG. 13.

FIG. 13 is an explanatory diagram illustrating an example of radioresources (the radio resources of the PRACH) not admitted as the D2Dresources. In FIG. 12, the timing of the PRACH when the PRACHconfiguration index is 0 is illustrated in the time direction, as inFIG. 6. For example, thus, the PRACH is located in the radio frames inwhich the SFN is even. Thus, when the PRACH is arranged, the D2Dresource decision unit 151 decides any radio resources excluding theradio resources of the PRACH as the D2D resources. Specifically, forexample, any radio resources of the radio frame among the radio framesin which the SFN is odd can be decided as the D2D resources. Asillustrated in FIG. 7, when the PRACH configuration index is 0, thePRACH is present in subframe #2. Therefore, any radio resources of thesubframe other than subframe #2 in the radio frame in which the SFN iseven can also be decided as the D2D resources.

Thus, the radio resources used in the radio access procedure are notdecided as the D2D resources, and thus the terminal devices 200 do notperform the D2D communication using the radio resources used in therandom access procedure. As a result, it is possible to prevent theterminal devices 200 from not performing the random access procedure dueto the D2D communication. As described above, in regard to the radioresources used in the random access procedure, when the D2D resourcesare the radio resources of the PRACH, the terminal devices 200 can beprevented from not transmitting the PRACH preamble due to the D2Dcommunication.

As another example, the radio resources used in the random accessprocedure may be radio resources selected in advance as the radioresources used in the random access procedure by the terminal devices200 performing the D2D communication. That is, when the radio resourcesused in the random access procedure other than the PRACH are selected inadvance, the D2D resource decision unit 151 may decide any radioresources excluding the pre-selected radio resources as the D2Dresources. The random access procedure includes not only transmission ofthe PRACH preamble by the terminal device 200 but also transmission of arandom access response with the Physical Downlink Shared CHannel (PDSCH)by the base station 100 and transmission of Contention ResolutionIdentity (CRI).

Thus, when the radio resources for the random access procedure otherthan the radio resources of the PRACH are also excluded from the targetof the D2D resources, the terminal device 200 does not perform the D2Dcommunication using any radio resources for the random access procedure.As a result, the terminal device 200 can be prevented from notperforming a part of the random access procedure due to the D2Dcommunication. From another viewpoint, the terminal device 200 canperform the D2D communication without influencing the random accessprocedure until a process of the random access procedure is completed.

As described above, for example, any radio resources excluding specificradio resources (for example, the radio resources for paging or theradio resources for the random access procedure) used by the terminaldevice 200 in the idle mode of the radio resource control are decided asthe D2D resources. Thus, when the terminal devices 200 are in the idlemode, the terminal devices 200 can perform the D2D communication withoutinfluencing cellular communication of the self-devices.

When the D2D communication is used for MTC, the D2D resources decided asdescribed above are particularly effective. The MTC is autonomouscommunication between devices. As an example of the MTC, a device whichis a measuring device transmits measurement data to a nearby device andthe nearby device collects the measurement data. In the MTC, the size ofdata to be transmitted is small, a transmission frequency of data islow, and transmission delay of data is allowed. Further, low cost andlow power consumption are necessary in the devices. Therefore, thedevices used for the MTC preferably perform the D2D communication whencommunication circuits are shared between the cellular communication andthe D2D communication and the devices are in the idle mode of thecellular communication. Accordingly, when the terminal devices 200 arethe devices performing the MTC, the D2D resources decided as describedabove are particularly effective.

Specific Example of Decided D2D Resources

For example, the D2D resource decision unit 151 decides the radioresources of one subframe not including the specific radio resources asthe radio resources available for the D2D communication. Hereinafter, aspecific example of this point will be described with reference to FIG.14.

FIG. 14 is an explanatory diagram illustrating an example of the decidedD2D resources. In FIG. 14, a radio frame number and a subframe numberare illustrated as the decided D2D resources. In this example, the radioresources of the subframe of which the subframe number is 3, 4, 7, 8 or9 are decided as the D2D resources among the radio frames in which theSFN is not even (that is, the radio frames in which the SFN is odd).

As illustrated in FIG. 13, when the PRACH configuration index is 0, thePRACH is present in the radio frames in which the SFN is even.Therefore, since the D2D resources illustrated in FIG. 14 are the radioresources of the radio frames in which the SFN is odd, the D2D resourcesdo not include the radio resources of the PRACH. Accordingly, the D2Dcommunication with the D2D resources does not interfere with thetransmission of the PRACH preamble.

As illustrated in FIG. 3, when the TDD configuration is configuration 0and the parameter Ns=2, the paging occasion can be subframe #0 andsubframe #5. Therefore, since the D2D resources illustrated in FIG. 14do not include subframe #0 and subframe #5, the D2D resources do notinclude the radio resources of the subframe of the paging occasion.Accordingly, the D2D communication with the D2D resources does notinterfere with the reception of the paging message.

Thus, by deciding the radio resources in units of subframes as the D2Dresources, the D2D resources can be indicated as simple information.Accordingly, it is possible to suppress the radio resources used whenthe terminal device 100 is notified of the D2D resources. Since the D2Dresources can be decided easily, the process of deciding the D2Dresources can be further simplified. Since the radio resources availablefor the cellular communication and the radio resources used for the D2Dcommunication are separated on the time axis, communication circuits(for example, RF circuits) can be shared between the cellularcommunication and the D2D communication.

For example, the decided D2D resources are used for the D2Dcommunication by the terminal devices 200 in the idle mode of the radioresource control and are not used for the D2D communication by theterminal devices 200 in the connection mode of the radio resourcecontrol. In general, there is a possibility of the terminal device 200in the connection mode receiving a downlink signal destined for theself-device with any subframe. Therefore, when the D2D communication isperformed, the terminal device 200 may fail to receive the downlinksignal. Therefore, only the terminal device 200 in the idle modeperforms the D2D communication using the D2D resources, and thus it ispossible to suppress the possibility of the D2D communicationinterfering with the cellular communication.

Modification of D2D Resources

The D2D resource decision unit 151 modifies the D2D resources asnecessary. That is, the D2D resource decision unit 151 decides new D2Dresources as necessary. For example, when the specific radio resources(for example, the radio resources for paging or the radio resources forthe random access procedure) are modified, the D2D resource decisionunit 151 decides new D2D resources.

In particular, in the embodiment, when the D2D resources are modified,the D2D resources before the modification are not used for the D2Dcommunication after a predetermined timing and the D2D resources afterthe modification are used for the D2D communication after thepredetermined timing. For example, there is no case where, when theterminal devices 200A and 200B perform the D2D communication, one of theterminal devices 200A and 200B uses the D2D resources before themodification and the other thereof uses the D2D resources after themodification.

Thus, the D2D resources used before and after the predetermined timingare switched, and thus it is possible to suppress an error in the D2Dcommunication. That is, it is possible to avoid occurrence of an errorin the D2D communication due to use of different D2D resources betweenthe terminal devices 200 performing the D2D communication.

(D2D Resource Notification Unit 153)

The D2D resource notification unit 153 notifies the terminal device 200located within the cell 10 of the D2D resources.

For example, the D2D resource notification unit 153 gives notificationof the D2D resources in the system information of the cell 10. Morespecifically, for example, the D2D resource notification unit 153generates the SIB including the information regarding the decided D2Dresources. Then, the D2D resource notification unit 153 causes the radiocommunication unit 120 to transmit the SIB using the radio resourcesused to transmit the SIB.

For example, when the D2D resources are modified (that is, the new D2Dresources are decided), the D2D resource notification unit 153 transmitsthe D2D resources after the modification. More specifically, forexample, as illustrated in FIG. 9, the D2D resource notification unit153 causes the radio communication unit 120 to transmit the systeminformation before the modification during the modification period (N)of the system information and to transmit the system information afterthe modification during the modification period (N+1) of the systeminformation.

Thus, by the notification of the D2D resources as the systeminformation, the D2D resources after the modification can be used duringthe modification period (N+1) of the system information after a timingat which the SIB including the D2D resources is first received. The D2Dresources before the modification are not used after this timing.Accordingly, since the D2D resources used before and after the timingare switched, it is possible to suppress an error in the D2Dcommunication.

As described above, for example, the D2D resources are any radioresources excluding the specific radio resources (for example, the radioresources for paging or the radio resources for the random accessprocedure). The specific radio resources are modified with modificationof the system information (for example, the paging period T and theparameter nB or the PRACH configuration index). Accordingly, when theD2D resources are transmitted in the system information, notification ofthe modified D2D resources can be given in a timely manner.

(D2D Resource Modification Notification Unit 155)

The D2D resource modification notification unit 155 gives notificationof the modification of the D2D resources through the paging when the D2Dresources are modified.

Thus, the notification of the modification of the D2D resources is giventhrough the paging, and thus even the terminal devices 200 in the idlemode can be aware of the D2D resources. Accordingly, the terminaldevices 200 in the idle mode can be allowed to use the radio resourcesadmitted in the D2D communication.

For example, the D2D resource modification notification unit 155 givesthe notification of the modification of the D2D resources as themodification of the system information through the paging. Morespecifically, for example, the D2D resource modification notificationunit 155 gives the notification of the modification of the D2D resourcesby setting the flag of the system information modification in the pagingmessage illustrated in FIG. 4 to 1 and causing the radio communicationunit 120 to transmit the paging message. For example, the D2D resourcemodification notification unit 155 causes the radio communication unit120 to transmit the paging message during the modification period (N) ofthe system information, as illustrated in FIG. 9. Then, the systeminformation after the modification including the information regardingthe D2D resources after the modification is transmitted during themodification period (N+1) of the system information.

Thus, the notification of the modification of the D2D resources can begiven without modification of the existing paging message.

The D2D resource modification notification unit 155 may give thenotification of the modification of the D2D resources as modificationdifferent from the modification of the system information through thepaging and may not give the notification of the modification of the D2Dresources as the modification of the system information through thepaging. Hereinafter, a specific example of this point will be describedwith reference to FIG. 15.

FIG. 15 is an explanatory diagram illustrating an example of informationincluded in the paging message according to the embodiment. Referring toFIG. 15, the paging message includes, for example, a paging record list,a flag of system information modification, and a flag of ETWSindication, as in the example illustrated in FIG. 4. The paging messagefurther includes a flag of D2D resource modification.

When the D2D resources are modified, the D2D resource modificationnotification unit 155 notifies the terminal devices 200 of themodification of the D2D resources by setting the flag of the D2Dresource modification to 1. When the D2D resources are not modified, theD2D resource modification notification unit 155 notifies the terminaldevices 200 of non-modification of the D2D resources by setting the flagof the D2D resource modification to 0. The D2D resource modificationnotification unit 155 decides the flag of the system informationmodification based on whether the system information other than theinformation regarding the D2D resources is modified. That is, the flagof the system information modification is not changed based on whetherthe D2D resources are modified.

Thus, it is possible to suppress a notification frequency of themodification of the system information while notifying the terminaldevices 200 of the modification of the D2D resources. Accordingly, theterminal device 200 not performing the D2D communication can beprevented from needlessly searching for a portion changed in the systeminformation.

4. Configuration of Terminal Device

Next, an example of the configuration of the terminal device 200according to the embodiment will be described with reference to FIGS. 16and 17. FIG. 16 is a block diagram illustrating an example of theconfiguration of the terminal device 200 according to the embodiment.Referring to FIG. 16, the terminal device 200 includes an antenna unit210, a radio communication unit 220, a storage unit 230, and a controlunit 240.

(Antenna Unit 210)

The antenna unit 210 receives a radio signal and outputs the receivedradio signal to the radio communication unit 220. The antenna unit 210transmits a transmission signal output by the radio communication unit220.

(Radio Communication Unit 220)

The radio communication unit 220 performs the radio communication withthe base station 100 of the cell 10 when the terminal device 200 islocated within the cell 10.

(Storage Unit 230)

The storage unit 230 stores a program and data used for an operation ofthe terminal device 200.

(Control Unit 240)

The control unit 240 supplies various functions of the terminal device200. The control unit 240 includes a D2D resource recognition unit 241,a D2D resource modification recognition unit 243, and a D2Dcommunication control unit 245.

(D2D Resource Recognition Unit 241)

The D2D resource recognition unit 241 recognizes the D2D resources whenthe D2D resources are decided and the notification of the D2D resourcesare given.

More specifically, for example, the notification of the D2D resourcesare given in the system information. In this case, when the radiocommunication unit 220 receives the SIB including the informationregarding the D2D resources, the D2D resource recognition unit 241recognizes the D2D resources from the SIB.

(D2D Resource Modification Recognition Unit 243)

When the D2D resources are modified and the notification of themodification of the D2D resources is given through the paging, the D2Dresource modification recognition unit 243 recognizes the modificationof the D2D resources.

More specifically, for example, as described above, the notification ofthe modification of the D2D resources is given as the modification ofthe system information through the paging. As illustrated in FIG. 9, thesystem information before the modification is transmitted during themodification period (N) of the system information and the systeminformation after the modification is transmitted during themodification period (N+1) of the system information. In this case, theradio communication unit 220 receives the paging message during themodification period (N) of the system information. Then, the D2Dresource modification recognition unit 243 recognizes the modificationof the system information from the flag of the system informationmodification in the paging message. This operation has been describedwith reference to FIG. 5. The radio communication unit 220 receives theSIB including the information regarding the D2D resources during themodification period (N+1) of the system information. Then, the D2Dresource modification recognition unit 243 acquires the informationregarding the D2D resources from the SIB and recognizes the modificationof the D2D resources.

The notification of the modification of the D2D resources may be givenas the modification different from the modification of the systeminformation through the paging and may not be given as the modificationof the of the system information through the paging. In this case, whenthe paging message illustrated in FIG. 14 is transmitted during themodification period (N) of the system information, the D2D resourcemodification recognition unit 243 may recognize the modification of theD2D resources from the flag of the D2D resource modification in thepaging message. Hereinafter, this operation will be described withreference to FIG. 17.

FIG. 17 is an explanatory diagram illustrating an example of anoperation of the terminal device in regard to the paging according tothe embodiment. Referring to FIG. 17, the terminal device in the idlemode first monitors whether the P-RNTI is present in the PDCCH in thesubframe of a predetermined paging occasion.

When the P-RNTI is present in the PDCCH in the subframe of the pagingoccasion, the paging message is included in the subframe. Accordingly,the D2D resource modification recognition unit 243 acquires the pagingmessage. As described above, the paging message includes the pagingrecord list, the flag of the system information modification, the flagof the ETWS indication, and the flag of the D2D resource modification.When the P-RNTI is not present in the PDCCH, the D2D resourcemodification recognition unit 243 monitors the PDCCH again in asubsequent paging occasion.

The D2D resource modification recognition unit 243 also checks, from theflag of the D2D resource modification, whether the D2D resources aremodified when the paging message is acquired.

(D2D Communication Control Unit 245)

The D2D communication control unit 245 controls the D2D communicationperformed by the terminal device 200.

In particular, in the embodiment, the D2D communication control unit 245controls the D2D communication so that the recognized D2D resources areused for the D2D communication. More specifically, for example, the D2Dcommunication control unit 245 causes the radio communication unit 220to perform the D2D communication using the D2D resources recognized bythe D2D resource recognition unit 241.

In the embodiment, when the D2D resources are modified, the D2Dcommunication control unit 245 controls the D2D communication such thatthe D2D resources before the modification are not used for the D2Dcommunication after a predetermined timing and the D2D resources afterthe modification are used for the D2D communication after thepredetermined timing. More specifically, for example, the notificationof the D2D resources is given in the system information. When the D2Dresources are modified, as described above, the D2D resourcemodification recognition unit 243 recognizes the modification of the D2Dresources. In this case, the D2D communication control unit 245 causesthe radio communication unit 220 to perform the D2D communication usingthe D2D resources before the modification until the modification of theD2D resources is recognized, and then causes the radio communicationunit 220 to perform the D2D communication using the D2D resources afterthe modification after the modification of the D2D resources isrecognized.

For example, when the terminal device 200 is in the RRC idle mode, theD2D communication control unit 245 performs the D2D communication usingthe D2D resources. When the terminal device 200 is in the RRC connectionmode, the D2D communication control unit 245 does not perform the D2Dcommunication using the D2D resources.

5. Flow of Process

Next, an example of a communication control process according to theembodiment will be described with reference to FIGS. 18 to 20.

(Communication Control Process on Base Station Side)

FIG. 18 is a flowchart illustrating an example of a schematic flow ofthe communication control process on the base station side according tothe embodiment.

In step S401, the D2D resource decision unit 151 decides the radioresources (that is, the D2D resources) available for the D2Dcommunication within the cell 10.

In step S500, the D2D resource decision unit 151 performs a D2D resourcemodification determination process. Then, when it is determined that theD2D resources are modified in the D2D resource modificationdetermination process in step S403, the process proceeds to step S405.Otherwise, the process proceeds to step S409.

In step S405, the D2D resource decision unit 151 decides new D2Dresources.

In step S407, the D2D resource modification notification unit 155 givesthe notification of the modification of the D2D resources through thepaging.

In step S409, the D2D resource notification unit 153 notifies theterminal devices 200 located within the cell 10 of the D2D resources.Then, the process returns to step S500.

D2D Resource Modification Determination Process

FIG. 19 is a flowchart illustrating an example of a schematic flow of aD2D resource modification determination process according to theembodiment.

In step S501, the D2D resource decision unit 151 determines whether thepaging occasion is modified. For example, based on whether the pagingperiod T and the parameter nB are modified, the D2D resource decisionunit 151 determines whether the paging occasion is modified. When thepaging occasion is modified, the process proceeds to step S507.Otherwise, the process proceeds to step S503.

In step S503, the D2D resource decision unit 151 determines whether anoccasion of random access (for example, the timing of the PRACH) ismodified. For example, based on whether the PRACH configuration index ismodified, the D2D resource decision unit 151 determines whether thetiming of the PRACH is modified. When the occasion of the random accessis modified, the process proceeds to step S507. Otherwise, the processproceeds to step S505.

In step S505, the D2D resource decision unit 151 determines that the D2Dresources are modified. Then, the process ends.

In step S507, the D2D resource decision unit 151 determines that the D2Dresources are not modified. Then, the process ends.

(Communication Control Process on Terminal Device Side)

FIG. 20 is a flowchart illustrating an example of a schematic flow of acommunication control process on the base station side according to theembodiment.

In step S601, the D2D resource recognition unit 241 recognizes the D2Dresources. For example, the D2D resource recognition unit 241 recognizesthe D2D resources from the SIB including the information regarding theD2D resources.

In step S603, the D2D communication control unit 245 controls the D2Dcommunication performed by the terminal devices 200. More specifically,for example, the D2D communication control unit 245 controls the D2Dcommunication so that the recognized D2D resources are used for the D2Dcommunication.

In step S605, the D2D resource modification recognition unit 243determines whether the D2D resources are modified. More specifically,for example, it is determined whether the D2D resources are modifiedbased on the flag of the system information modification in the pagingmessage and the information regarding the D2D resources in one SIB. Whenthe D2D resources are modified, the process returns to step S601.Otherwise, the process returns to step S603.

6. Modification Example

Next, a modification example of the embodiment will be described withreference to FIGS. 21 to 23.

6.1. Overview

First, an overview of a modification example of the base station 100according to the embodiment will be described with reference to FIG. 21.

In the above-described embodiment, the D2D resources are decided as thecommon resources to the terminal devices 200 located within the cell 10.On the other hand, in a modification example of the embodiment, the D2Dresources are decided for each group of the D2D communication. Thedecision of the D2D resources for each group can result in severaladvantages as follows.

First, more radio resources can be used for the D2D communication in thegroups of the D2D communication. More specifically, the radio resourcespermitted to be used for the D2D communication may differ depending on aD2D group. For example, since the paging occasion differs depending onthe terminal device 200, the radio resources for paging can differdepending on the D2D group. Accordingly, when the radio resources forthe D2D communication are decided for each D2D group, the amount ofradio resources to be excluded can be set to be smaller. As a result,more radio resources can be decided as the D2D resources in each groupof the D2D communication, and thus more radio resources can be used.

Second, by deciding the D2D resources so that the D2D resources do notoverlap between the groups of the D2D communication, it is possible tosuppress interference between the groups of the D2D communication.Hereinafter, a specific example of this point will be described withreference to FIG. 21.

FIG. 21 is an explanatory diagram illustrating an example of theinterference between the groups of D2D communication. Referring to FIG.21, the terminal devices 200A and 200B perform the D2D communication inthe radio communication system 1. That is, the terminal devices 200A and200B form a group of the D2D communication. Further, terminal devices200C and 200D perform the D2D communication. That is, the terminaldevices 200C and 200D also form a group of the D2D communication. Inthis example, the group of the terminal devices 200A and 200B and thegroup of the terminal devices 200C and 200D are located near each other.Accordingly, interference can occur between the groups.

Thus, the interference can occur between the groups of the D2Dcommunication. Accordingly, by deciding the radio resources availablefor the D2D communication for each group of the D2D communication sothat the D2D resources do not overlap between the groups of the D2Dcommunication, it is possible to suppress the interference between thegroups of the D2D communication.

6.2. Configuration of Base Station

First, an example of the configuration of the base station 100 accordingto the modification example of the embodiment will be described withreference to FIG. 22. Here, only differences from the example of theconfiguration of the base station 100 according to the above-describedembodiment or modifications from this example will be described.

(D2D Resource Decision Unit 151)

The D2D resource decision unit 151 decides the radio resources (that is,D2D resources) available for the D2D communication for each group of theD2D communication.

For example, the D2D resource decision unit 151 decides the D2Dresources so that the D2D resources do not overlap between the groups ofthe D2D communication. More specifically, for example, the D2D resourcedecision unit 151 decides the D2D resources so that the D2D resources donot overlap between any groups of the D2D communication. Hereinafter, aspecific example of this point will be described with reference to FIG.22.

FIG. 22 is an explanatory diagram illustrating an example of the D2Dresources decided for each group of the D2D communication. FIG. 22illustrates the D2D resources of each group when 3 groups (groups A, B,and C) of the D2D communication are present. As in the example of FIG.14, a radio frame number and a subframe number are illustrated as theD2D resources. In this example, the radio resources of a subframe inwhich the subframe number is 3 or 4 in the radio frames in which the SFNis not even (that is, the radio frames in which the SFN is odd) aredecided as the D2D resources of the group A. The radio resources of asubframe in which the subframe number is 7 or 8 in the radio frames inwhich the SFN is not even are decided as the D2D resources of the groupB. The radio resources of a subframe in which the subframe number is 9in the radio frames in which the SFN is not even are decided as the D2Dresources of the group C.

Thus, by deciding the D2D resources so that the D2D resources do notoverlap between the groups of the D2D communication, as described above,it is possible to suppress the interference between the groups of theD2D communication.

The D2D resource decision unit 151 may decide the D2D resources so thatthe D2D resources do not overlap between a first group of the D2Dcommunication and a second group of the D2D communication located nearthe first group. That is, when the groups of the D2D communication arelocated near each other, the D2D resources may not overlap between thesegroups, instead of overlapping between any groups of the D2Dcommunication.

Specifically, for example, the D2D resource decision unit 151 recognizesthe groups of the D2D communication located near each other. Forexample, the groups A and B are recognized. Thereafter, the D2D resourcedecision unit 151 decides the D2D resources of each of the groups A andB so that the D2D resources do not overlap between the groups A and B.

Thus, it is possible to suppress the interference between the groups ofthe D2D communication. Since the same radio resources can be usedbetween the groups of the D2D communication which are not located neareach other, more radio resources can be used for the D2D communication.

The D2D resource decision unit 151 can recognize the groups of the D2Dcommunication located near each other as follows, for example. First,the D2D resource decision unit 151 estimates a distance between the basestation 100 and the terminal device 200 from a timing advance value inregard to the terminal device 200 and estimates the direction of theterminal device 200 from the base station 100 based on a receptionresult of the antenna. Then, the D2D resource decision unit 151recognizes the groups including the terminal devices 200 of which thedistance and the direction are close as the groups of the D2Dcommunication located near each other.

(D2D Resource Notification Unit 153)

The D2D resource notification unit 153 gives the notification of the D2Dresources decided for each group of the D2D communication. Morespecifically, for example, the D2D resource notification unit 153generates the SIB including the information regarding the D2D resourcesdecided for each group of the D2D communication, as illustrated in FIG.22. Then, the D2D resource notification unit 153 causes the radiocommunication unit 120 to transmit the SIB using the radio resourcesused to transmit the SIB.

6.3. Flow of Process

Next, an example of the communication control process according to themodification example of the embodiment will be described with referenceto FIG. 23. A communication control process of the terminal device sideis not different between the communication control process according tothe above-described embodiment and the communication control processaccording to the modification. Accordingly, only the communicationcontrol process of the base station side will be described here.

FIG. 23 is a flowchart illustrating an example of a schematic flow ofthe communication control process on the base station side according tothe modification example of the embodiment.

In step S701, the D2D resource decision unit 151 decides the radioresources (that is the D2D resources) available for the D2Dcommunication for each group of the D2D communication.

In step S500, the D2D resource decision unit 151 performs the D2Dresource modification determination process. Then, when the D2Dresources are determined to be modified in the D2D resource modificationdetermination process in step S703, the process proceeds to step S705.Otherwise, the process proceeds to step S709.

In step S705, the D2D resource decision unit 151 decides new D2Dresources for each group of the D2D communication.

In step S707, the D2D resource modification notification unit 155 givesthe notification of the modification of the D2D resources through thepaging.

In step S709, the D2D resource notification unit 153 notifies theterminal devices 200 located within the cell 10 of the D2D resources ofeach group. Then, the process returns to step S500.

7. Application

The technology related to the present disclosure can be applied tovarious products. For example, the base station 100 may be realized asone kind of evolved NodeB (eNB) such as a macro eNB or a small eNB. Thesmall eNB may be an eNB that covers a smaller cell, such as a pico eNB,a micro eNB, or a home (pemto) eNB, than a macro cell. Instead, the basestation 100 may be realized as another kind of base station such as aNodeB or a base transceiver station (BTS). The base station 100 mayinclude a main body (also referred to as a base station device)controlling radio communication and at least one remote radio head (RRH)disposed at a different location than the main body. The various kindsof terminals described below may perform a base station functiontemporarily or semi-permanently to operate as the base station 100.

The terminal device 200 may be realized as, for example, a mobileterminal such as a smartphone, a tablet personal computer (PC), anotebook PC, a portable game console, a portable/dongle-style mobilerouter, or a digital camera, or as an in-vehicle terminal such as a carnavigation device. In addition, the terminal device 200 may also berealized as a terminal that conducts machine-to-machine (M2M)communication (also called a machine-type communication (MTC) terminal).Furthermore, the terminal device 200 may be a radio communication modulemounted onboard these terminals (for example, an integrated circuitmodule configured on a single die).

4.1. Application Example of Base Station

(First Application)

FIG. 24 is a block diagram illustrating a first example of a schematicconfiguration of an eNB to which technology according to an embodimentof the present disclosure may be applied. An eNB 800 includes one ormore antennas 810, and a base station device 820. The respectiveantennas 810 and the base station device 820 may be connected to eachother via an RF cable.

Each antenna 810 includes a single or a plurality of antenna elements(for example, a plurality of antenna elements constituting a MIMOantenna), and is used by the base station device 820 to transmit andreceive radio signals. The eNB 800 may include a plurality of antennas810 as illustrated in FIG. 24, and the plurality of antennas 810 mayrespectively correspond to a plurality of frequency bands used by theeNB 800, for example. Note that although FIG. 24 illustrates an exampleof the eNB 800 including a plurality of antennas 810, the eNB 800 mayalso include a single antenna 810.

The base station device 820 is equipped with a controller 821, memory822, a network interface 823, and a radio communication interface 825.

The controller 821 may be a CPU or DSP, for example, and causes varioushigher-layer functions of the base station device 820 to operate. Forexample, the controller 821 generates a data packet from data inside asignal processed by the radio communication interface 825, and forwardsthe generated packet via the network interface 823. The controller 821may also generate a bundled packet by bundling data from a plurality ofbaseband processors, and forward the generated bundled packet. Inaddition, the controller 821 may also include logical functions thatexecute controls such as Radio Resource Control (RRC), Radio Bearercontrol, mobility management, admission control, or scheduling. Also,such controls may also be executed in coordination with a nearby eNB orcore network node. The memory 822 includes RAM and ROM, and storesprograms executed by the controller 821 as well as various control data(such as a terminal list, transmit power data, and scheduling data, forexample).

The network interface 823 is a communication interface for connectingthe base station device 820 to a core network 824. The controller 821may also communication with a core network node or another eNB via thenetwork interface 823. In this case, the eNB 800 and the core networknode or other eNB may be connected to each other by a logical interface(for example, the Si interface or the X2 interface). The networkinterface 823 may also be a wired communication interface, or a wirelesscommunication interface for wireless backhaul. In the case in which thenetwork interface 823 is a wireless communication interface, the networkinterface 823 may use a higher frequency band for wireless communicationthan the frequency band used by the radio communication interface 825.

The radio communication interface 825 supports a cellular communicationscheme such as Long Term Evolution (LTE) or LTE-Advanced, and provides aradio connection to a terminal positioned inside the cell of the eNB 800via an antenna 810. Typically, the radio communication interface 825 mayinclude a baseband (BB) processor 826, an RF circuit 827, and the like.The BB processor 826 may conduct processes such as encoding/decoding,modulation/demodulation, and multiplexing/demultiplexing, for example,and executes various signal processing in respective layers (forexample, L1, Medium Access Control (MAC), Radio Link Control (RLC), andPacket Data Convergence Protocol (PDCP)). The BB processor 826 may alsoinclude some or all of the logical functions discussed earlier insteadof the controller 821. The BB processor 826 may be a module includingmemory that stores a communication control program, a processor thatexecutes such a program, and related circuits. The functions of the BBprocessor 826 may also be modifiable by updating the program. Also, themodule may be a card or a blade inserted into a slot of the base stationdevice 820, or a chip mounted onboard the card or the blade. Meanwhile,the RF circuit 827 may include components such as a mixer, a filter, andan amp, and transmits or receives a radio signal via an antenna 810.

The radio communication interface 825 may also include a plurality of BBprocessors 826 as illustrated in FIG. 24, and the plurality of BBprocessors 826 may respectively correspond to a plurality of frequencybands used by the eNB 800, for example. In addition, the radiocommunication interface 825 may also include a plurality of RF circuits827 as illustrated in FIG. 24, and the plurality of RF circuits 827 mayrespectively correspond to a plurality of antenna elements, for example.Note that although FIG. 24 illustrates an example of the radiocommunication interface 825 including a plurality of BB processors 826and a plurality of RF circuits 827, the radio communication interface825 may also include a single BB processor 826 or a single RF circuit827.

(Second Application)

FIG. 25 is a block diagram illustrating a second example of a schematicconfiguration of an eNB to which technology according to an embodimentof the present disclosure may be applied. An eNB 830 includes one ormore antennas 840, a base station device 850, and an RRH 860. Therespective antennas 840 and the RRH 860 may be connected to each othervia an RF cable. Also, the base station device 850 and the RRH 860 maybe connected to each other by a high-speed link such as an optical fibercable.

Each antenna 840 includes a single or a plurality of antenna elements(for example, a plurality of antenna elements constituting a MIMOantenna), and is used by the RRH 860 to transmit and receive radiosignals. The eNB 830 may include a plurality of antennas 840 asillustrated in FIG. 25, and the plurality of antennas 840 mayrespectively correspond to a plurality of frequency bands used by theeNB 830, for example. Note that although FIG. 25 illustrates an exampleof the eNB 830 including a plurality of antennas 840, the eNB 830 mayalso include a single antenna 840.

The base station device 850 is equipped with a controller 851, memory852, a network interface 853, a radio communication interface 855, and aconnection interface 857. The controller 851, the memory 852, and thenetwork interface 853 are similar to the controller 821, the memory 822,and the network interface 823 described with reference to FIG. 24.

The radio communication interface 855 supports a cellular communicationscheme such as LTE or LTE-Advanced, and provides a radio connection to aterminal positioned inside a sector corresponding to the RRH 860 via theRRH 860 and an antenna 840. Typically, the radio communication interface855 may include a BB processor 856 and the like. The BB processor 856 issimilar to the BB processor 826 described with reference to FIG. 24,except for being connected to an RF circuit 864 of the RRH 860 via theconnection interface 857. The radio communication interface 855 may alsoinclude a plurality of BB processors 856 as illustrated in FIG. 25, andthe plurality of BB processors 856 may respectively correspond to aplurality of frequency bands used by the eNB 830, for example. Note thatalthough FIG. 25 illustrates an example of the radio communicationinterface 855 including a plurality of BB processors 856, the radiocommunication interface 855 may also include a single BB processor 856.

The connection interface 857 is an interface for connecting the basestation device 850 (radio communication interface 855) to the RRH 860.The connection interface 857 may also be a communication module forcommunication on the high-speed link connecting the base station device850 (radio communication interface 855) and the RRH 860.

In addition, the RRH 860 is equipped with a connection interface 861 anda radio communication interface 863.

The connection interface 861 is an interface for connecting the RRH 860(radio communication interface 863) to the base station device 850. Theconnection interface 861 may also be a communication module forcommunication on the high-speed link.

The radio communication interface 863 transmits and receives a radiosignal via an antenna 840. Typically, the radio communication interface863 may include an RF circuit 864. The RF circuit 864 may includecomponents such as a mixer, a filter, and an amp, and transmits orreceives a radio signal via an antenna 840. The radio communicationinterface 863 may also include a plurality of RF circuits 864 asillustrated in FIG. 25, and the plurality of RF circuits 864 mayrespectively correspond to a plurality of antenna elements, for example.Note that although FIG. 25 illustrates an example of the radiocommunication interface 863 including a plurality of RF circuits 864,the radio communication interface 863 may also include a single RFcircuit 864.

In the eNB 800 and the eNB 830 illustrated in FIGS. 24 and 25, the D2Dresource decision unit, the D2D resource notification unit, and the D2Dresource modification notification unit described with reference to FIG.11 may be implemented in the radio communication interface 825 as wellas the radio communication interface 855 and/or the radio communicationinterface 863. Also, at least some of these functions may also beimplemented in the controller 821 and the controller 851.

4.2. Application Example of Terminal Device

(First Application)

FIG. 26 is a block diagram illustrating an example of a schematicconfiguration of a smartphone 900 to which technology according to anembodiment of the present disclosure may be applied. The smartphone 900is equipped with a processor 901, memory 902, storage 903, an externalconnection interface 904, a camera 906, a sensor 907, a microphone 908,an input device 909, a display device 910, a speaker 911, a radiocommunication interface 912, one or more antenna switches 915, one ormore antennas 916, a bus 917, a battery 918, and an auxiliary controller919.

The processor 901 may be a CPU or system-on-a-chip (SoC), for example,and controls functions in the application layer and other layers of thesmartphone 900. The memory 902 includes RAM and ROM, and stores programsexecuted by the processor 901 as well as data. The storage 903 mayinclude a storage medium such as semiconductor memory or a hard disk.The external connection interface 904 is an interface for connecting anexternally attached device, such as a memory card or Universal SerialBus (USB) device, to the smartphone 900.

The camera 906 includes an image sensor such as a charge-coupled device(CCD) or complementary metal-oxide-semiconductor (CMOS) sensor, andgenerates a captured image. The sensor 907 may include a sensor groupsuch as a positioning sensor, a gyro sensor, a geomagnetic sensor, andan acceleration sensor, for example. The microphone 908 converts audioinput into the smartphone 900 into an audio signal. The input device 909includes devices such as a touch sensor that detects touches on a screenof the display device 910, a keypad, a keyboard, buttons, or switches,and receives operations or information input from a user. The displaydevice 910 includes a screen such as a liquid crystal display (LCD) oran organic light-emitting diode (OLED) display, and displays an outputimage of the smartphone 900. The speaker 911 converts an audio signaloutput from the smartphone 900 into audio.

The radio communication interface 912 supports a cellular communicationscheme such as LTE or LTE-Advanced, and executes radio communication.Typically, the radio communication interface 912 may include a BBprocessor 913, an RF circuit 914, and the like. The BB processor 913 mayconduct processes such as encoding/decoding, modulation/demodulation,and multiplexing/demultiplexing, for example, and executes varioussignal processing for radio communication. Meanwhile, the RF circuit 914may include components such as a mixer, a filter, and an amp, andtransmits or receives a radio signal via an antenna 916. The radiocommunication interface 912 may also be a one-chip module integratingthe BB processor 913 and the RF circuit 914. The radio communicationinterface 912 may also include a plurality of BB processors 913 and aplurality of RF circuits 914 as illustrated in FIG. 26. Note thatalthough FIG. 26 illustrates an example of the radio communicationinterface 912 including a plurality of BB processors 913 and a pluralityof RF circuits 914, the radio communication interface 912 may alsoinclude a single BB processor 913 or a single RF circuit 914.

Furthermore, in addition to a cellular communication scheme, the radiocommunication interface 912 may also support other types of radiocommunication schemes such as a short-range wireless communicationscheme, a near field wireless communication scheme, or a wireless localarea network (LAN) scheme. In this case, a BB processor 913 and an RFcircuit 914 may be included for each radio communication scheme.

Each antenna switch 915 switches the destination of an antenna 916 amonga plurality of circuits included in the radio communication interface912 (for example, circuits for different radio communication schemes).

Each antenna 916 includes a single or a plurality of antenna elements(for example, a plurality of antenna elements constituting a MIMOantenna), and is used by the radio communication interface 912 totransmit and receive radio signals. The smartphone 900 may also includea plurality of antennas 916 as illustrated in FIG. 26. Note thatalthough FIG. 26 illustrates an example of the smartphone 900 includinga plurality of antennas 916, the smartphone 900 may also include asingle antenna 916.

Furthermore, the smartphone 900 may also be equipped with an antenna 916for each radio communication scheme. In this case, the antenna switch915 may be omitted from the configuration of the smartphone 900.

The bus 917 interconnects the processor 901, the memory 902, the storage903, the external connection interface 904, the camera 906, the sensor907, the microphone 908, the input device 909, the display device 910,the speaker 911, the radio communication interface 912, and theauxiliary controller 919. The battery 918 supplies electric power to therespective blocks of the smartphone 900 illustrated in FIG. 26 via powersupply lines partially illustrated with dashed lines in the drawing. Theauxiliary controller 919 causes minimal functions of the smartphone 900to operate while in a sleep mode, for example.

In the smartphone 900 illustrated in FIG. 26, the D2D resourcerecognition unit 241, the D2D resource modification recognition unit243, and the D2D communication control unit described with reference toFIG. 16 may be implemented in the radio communication interface 912.Also, at least some of these functions may also be implemented in theprocessor 901 or the auxiliary controller 919.

(Second Application)

FIG. 27 is a block diagram illustrating an example of a schematicconfiguration of a car navigation device 920 to which technologyaccording to an embodiment of the present disclosure may be applied. Thecar navigation device 920 is equipped with a processor 921, memory 922,a Global Positioning System (GPS) module 924, a sensor 925, a datainterface 926, a content player 927, a storage medium interface 928, aninput device 929, a display device 930, a speaker 931, a radiocommunication interface 933, one or more antenna switches 936, one ormore antennas 937, and a battery 938.

The processor 921 may be a CPU or SoC, for example, and controls a carnavigation function and other functions of the car navigation device920. The memory 922 includes RAM and ROM, and stores programs executedby the processor 921 as well as data.

The GPS module 924 measures the position of the car navigation device920 (for example, the latitude, longitude, and altitude) by using GPSsignals received from GPS satellites. The sensor 925 may include asensor group such as a gyro sensor, a geomagnetic sensor, and abarometric pressure sensor, for example. The data interface 926 isconnected to an in-vehicle network 941 via a port not illustrated in thedrawing, and acquires data generated on the vehicle side, such asvehicle speed data.

The content player 927 plays content stored on a storage medium (forexample, a CD or DVD) inserted into the storage medium interface 928.The input device 929 includes devices such as a touch sensor thatdetects touches on a screen of the display device 930, buttons, orswitches, and receives operations or information input from a user. Thedisplay device 930 includes a screen such as an LCD or OLED display, anddisplays a navigation function or an image of played-back content. Thespeaker 931 outputs audio of a navigation function or played-backcontent.

The radio communication interface 933 supports a cellular communicationscheme such as LTE or LTE-Advanced, and executes radio communication.Typically, the radio communication interface 933 may include a BBprocessor 934, an RF circuit 935, and the like. The BB processor 934 mayconduct processes such as encoding/decoding, modulation/demodulation,and multiplexing/demultiplexing, for example, and executes varioussignal processing for radio communication. Meanwhile, the RF circuit 935may include components such as a mixer, a filter, and an amp, andtransmits or receives a radio signal via an antenna 937. The radiocommunication interface 933 may also be a one-chip module integratingthe BB processor 934 and the RF circuit 935. The radio communicationinterface 933 may also include a plurality of BB processors 934 and aplurality of RF circuits 935 as illustrated in FIG. 27. Note thatalthough FIG. 27 illustrates an example of the radio communicationinterface 933 including a plurality of BB processors 934 and a pluralityof RF circuits 935, the radio communication interface 933 may alsoinclude a single BB processor 934 or a single RF circuit 935.

Furthermore, in addition to a cellular communication scheme, the radiocommunication interface 933 may also support other types of radiocommunication schemes such as a short-range wireless communicationscheme, a near field wireless communication scheme, or a wireless LANscheme. In this case, a BB processor 934 and an RF circuit 935 may beincluded for each radio communication scheme.

Each antenna switch 936 switches the destination of an antenna 937 amonga plurality of circuits included in the radio communication interface933 (for example, circuits for different radio communication schemes).

Each antenna 937 includes a single or a plurality of antenna elements(for example, a plurality of antenna elements constituting a MIMOantenna), and is used by the radio communication interface 933 totransmit and receive radio signals. The car navigation device 920 mayalso include a plurality of antennas 937 as illustrated in FIG. 27. Notethat although FIG. 27 illustrates an example of the car navigationdevice 920 including a plurality of antennas 937, the car navigationdevice 920 may also include a single antenna 937.

Furthermore, the car navigation device 920 may also be equipped with anantenna 937 for each radio communication scheme. In this case, theantenna switch 936 may be omitted from the configuration of the carnavigation device 920.

The battery 938 supplies electric power to the respective blocks of thecar navigation device 920 illustrated in FIG. 27 via power supply linespartially illustrated with dashed lines in the drawing. Also, thebattery 938 stores electric power supplied from the vehicle.

In the car navigation device 920 illustrated in FIG. 27, the D2Dresource recognition unit 241, the D2D resource modification recognitionunit 243, and the D2D communication control unit 245 described withreference to FIG. 16 may be implemented in the radio communicationinterface 933. Also, at least some of these functions may also beimplemented in the processor 921.

In addition, technology according to the present disclosure may also berealized as an in-vehicle system (or vehicle) 940 that includes one ormore blocks of the car navigation device 920 discussed above, thein-vehicle network 941, and a vehicle-side module 942. The vehicle-sidemodule 942 generates vehicle-side data such as the vehicle speed, numberof engine revolutions, or malfunction information, and outputs thegenerated data to the in-vehicle network 941.

8. Conclusion

The communication devices and each process according to the embodimenthave been described above with reference to FIGS. 1 to 23. According tothe embodiment of the present disclosure, the radio resources (that is,the D2D resources) available for the D2D communication within the cell10 are decided. Then, the terminal devices 200 located within the cell10 are notified of the D2D resources. When the D2D resources aremodified, the notification of the modification of the D2D resources isgiven through the paging. When the D2D resources are modified, the D2Dresources before the modification are not used for the D2D communicationafter a predetermined timing and the D2D resources after themodification are used for the D2D communication after the predeterminedtiming.

Thus, by the notification of the modification of the D2D resourcesthrough the paging, even the terminal device 200 in the idle mode can beaware of the D2D resources. Accordingly, the terminal device 200 in theidle mode can be allowed to use the radio resources admitted in the D2Dcommunication. Further, by switching the D2D resources used before andafter the predetermined timing, it is possible to suppress an error inthe D2D communication. That is, it is possible to avoid occurrence of anerror in the D2D communication due to use of different D2D resourcesbetween the terminal devices 200 performing the D2D communication. Thatis, the terminal device in the idle mode of the cellular communicationcan be allowed to use the radio resources admitted in the D2Dcommunication, and thus it is possible to suppress an error in the D2Dcommunication.

For example, the notification of the D2D resources is given in thesystem information of the cell 10.

Thus, during the modification period (N+1) of the system information,the D2D resources after the modification can be used after the timing atwhich the SIB including the D2D resources is first received. After thistiming, the D2D resources before the modification are not used.Accordingly, since the D2D resources used before and after the timingare switched, it is possible to suppress an error in the D2Dcommunication.

For example, the D2D resources are any radio resources excluding thespecific radio resources (for example, the radio resources for paging orthe radio resources for the random access procedure). The specific radioresources are modified with modification of the system information (forexample, the paging period T and the parameter nB or the PRACHconfiguration index). Accordingly, when the D2D resources aretransmitted in the system information, the notification of the modifiedD2D resources can be given in a timely manner.

For example, the radio resources (hereinafter referred to as “D2Dresources”) available for the D2D communication within the cell 10 aredecided based on the information regarding the specific radio resourcesused by the terminal device 200 in the idle mode of the radio resourcecontrol. More specifically, for example, any radio resources excludingthe specific radio resources are decided as the D2D resources.

Thus, when the terminal devices 200 are in the idle mode, the terminaldevices 200 can perform the D2D communication without influencingcellular communication of the self-devices.

When the D2D communication is used for MTC, the D2D resources decided asdescribed above are particularly effective. The MTC is autonomouscommunication between devices. As an example of the MTC, a device whichis a measuring device transmits measurement data to a nearby device andthe nearby device collects the measurement data. In the MTC, the size ofdata to be transmitted is small, a transmission frequency of data islow, and transmission delay of data is allowed. Further, low cost andlow power consumption are necessary in the devices. Therefore, thedevices used for the MTC preferably perform the D2D communication whencommunication circuits are shared between the cellular communication andthe D2D communication and the devices are in the idle mode of thecellular communication. Accordingly, when the terminal devices 200 arethe devices performing the MTC, the D2D resources decided as describedabove are particularly effective.

For example, the specific radio resources include the radio resourcesfor paging.

Thus, the radio resources for paging are not decided as the D2Dresources, and thus the terminal device 200 does not perform the D2Dcommunication with the radio resources for paging. As a result, theterminal device 200 can be prevented from not receiving the pagingmessage due to the D2D communication.

The radio resources for paging may be radio resources used for thepaging in regard to the terminal devices 200 performing the D2Dcommunication within the cell 10.

Thus, when only the radio resources for paging in regard to the terminaldevices 200 actually performing the D2D communication are excluded froma target of the D2D resources rather than all of the radio resources forpaging, more radio resources can be admitted as the D2D resources. As aresult, off-loading in regard to more traffic can be realized. That is,it is possible to suppress consumption of the radio resources andprocessing loads in an RAN.

For example, the specific radio resources include radio resources usedin the random access procedure for transition to the connection mode ofthe radio resource control.

Thus, the radio resources used in the random access procedure are notdecided as the D2D resources, and thus the terminal device 200 does notperform the D2D communication with the radio resources used in therandom access procedure. As a result, the terminal device 200 can beprevented from not performing the random access procedure due to the D2Dcommunication.

For example, the radio resources used in the random access procedure areradio resources of the PRACH.

Thus, the terminal device 200 can be prevented from not transmitting thePRACH preamble due to the D2D communication.

As another example, the radio resources used in the random accessprocedure may be the radio resources selected in advance as the radioresources used in the random access procedure by the terminal devices200 performing the D2D communication.

Thus, when the radio resources for the random access procedure otherthan the radio resources of the PRACH are also excluded from the targetof the D2D resources, the terminal device 200 does not perform the D2Dcommunication using any radio resources for the random access procedure.As a result, the terminal device 200 can be prevented from notperforming a part of the random access procedure due to the D2Dcommunication. From another viewpoint, the terminal device 200 canperform the D2D communication without influencing the random accessprocedure until a process of the random access procedure is completed.

For example, the radio resources of any subframe which does not includethe specific radio resources are decided as the radio resourcesavailable for the D2D communication.

Thus, the D2D resources can be indicated as simple information.Accordingly, it is possible to suppress the radio resources used whenthe terminal device 100 is notified of the D2D resources. Since the D2Dresources can be decided easily, the process of deciding the D2Dresources can be further simplified. Since the radio resources availablefor the cellular communication and the radio resources used for the D2Dcommunication are separated on the time axis, communication circuits(for example, RF circuits) can be shared between the cellularcommunication and the D2D communication.

For example, the decided D2D resources are used for the D2Dcommunication by the terminal devices 200 in the idle mode of the radioresource control and are not used for the D2D communication by theterminal devices 200 in the connection mode of the radio resourcecontrol.

In general, there is a possibility of the terminal device 200 in theconnection mode receiving a downlink signal destined for the self-devicewith any subframe. Therefore, when the D2D communication is performed,the terminal device 200 may fail to receive the downlink signal.Therefore, only the terminal device 200 in the idle mode performs theD2D communication using the D2D resources, and thus it is possible tosuppress the possibility of the D2D communication interfering with thecellular communication.

For example, the notification of the modification of the D2D resourcesis given as the modification of the system information through thepaging.

Thus, the notification of the modification of the D2D resources can begiven without modification of the existing paging message.

The notification of the modification of the D2D resources may be givenas modification different from the modification of the systeminformation through the paging and the modification of the D2D resourcesand may not be given as the modification of the system informationthrough the paging.

Thus, it is possible to suppress a notification frequency of themodification of the system information while notifying the terminaldevices 200 of the modification of the D2D resources. Accordingly, theterminal device 200 not performing the D2D communication can beprevented from needlessly searching for a portion changed in the systeminformation.

For example, according to the modification example of the embodiment ofthe present disclosure, the D2D resources are decided for each group ofthe D2D communication. Then, the notification of the D2D resourcesdecided for each group of the D2D communication is given.

Thus, more radio resources can be used for the D2D communication in thegroups of the D2D communication. More specifically, the radio resourcespermitted to be used for the D2D communication without problem maydiffer depending on a D2D group. For example, since the paging occasiondiffers depending on the terminal device 200, the radio resources forpaging can differ depending on the D2D group. Accordingly, when theradio resources for the D2D communication are decided for each D2Dgroup, the amount of radio resources to be excluded can be set to besmaller. As a result, more radio resources can be decided as the D2Dresources in each group of the D2D communication, and thus more radioresources can be used.

For example, the D2D resources are decided so that the D2D resources donot overlap between the groups of the D2D communication.

Thus, it is possible to suppress the interference between the groups ofthe D2D communication.

The D2D resources may be decided so that the D2D resources do notoverlap between a first group of the D2D communication and a secondgroup of the D2D communication located near the first group.

Thus, it is possible to suppress the interference between the groups ofthe D2D communication. Since the same radio resources can be usedbetween the groups of the D2D communication which are not located neareach other, more radio resources can be used for the D2D communication.

The preferred embodiments of the present disclosure have been describedabove with reference to the accompanying drawings, whilst the presentdisclosure is not limited to the above examples, of course. A personskilled in the art may find various alterations and modifications withinthe scope of the appended claims, and it should be understood that theywill naturally come under the technical scope of the present disclosure.

For example, the example in which the notification of the D2D resourcesis given in the system information of the cell has been described, butan embodiment of the present disclosure is not limited thereto. Forexample, the notification of the D2D resources may be given throughsignaling to an individual terminal device (by the D2D resourcenotification unit). When the D2D resources are modified, the D2Dresources before the modification may not be used for the D2Dcommunication after a predetermined timing and the D2D resources afterthe modification may be used for the D2D communication after thepredetermined timing. For example, the predetermined timing may be amodification timing of the system information. As another example, thepredetermined timing may be a start time point of the radio frame of adesignated SFN.

The example in which the duplex communication scheme to be adopted isTDD has been described, but an embodiment of the present disclosure isnot limited thereto. For example, the duplex communication scheme to beadopted may be FDD. Even in this case, the determination, notification,and modification notification of the D2D resources may be performed asin TDD.

The example in which the D2D communication is performed according toOFDM has been described, but an embodiment of the present disclosure isnot limited thereto. Another multiplexing scheme may be used for the D2Dcommunication.

The example in which the terminal device performs MTC has beendescribed, but an embodiment of the present disclosure is not limitedthereto. An embodiment of the present disclosure can also be applied toa radio communication system which does not perform MTC. That is, theterminal device may be a device that performs MTC or may be a terminaldevice that does not perform MTC. For example, an embodiment of thepresent disclosure may also be applied to a general terminal deviceconforming to LTE.

Also, the processing steps in a communication control process in thisspecification are not strictly limited to being executed in a timeseries following the sequence described in a flowchart. For example, theprocessing steps in a communication control process may be executed in asequence that differs from a sequence described herein as a flowchart,and furthermore may be executed in parallel.

In addition, it is possible to create a computer program for causinghardware such as a CPU, ROM, and RAM built into a communication controldevice (for example, terminal device) to exhibit functions similar toeach structural element of the foregoing communication control device.It becomes also possible to provide a storage medium which stores thecomputer program.

Additionally, the present technology may also be configured as below.

(1)

A communication control device including:

a decision unit configured to decide radio resources available forinter-device communication within a cell; and

a notification unit configured to notify a terminal device locatedwithin the cell of the radio resources,

wherein, when the radio resources are modified, the notification unitgives notification of modification of the radio resources throughpaging, and

wherein, when the radio resources are modified, the radio resourcesbefore the modification refrain from being used for the inter-devicecommunication after a predetermined timing and the radio resources afterthe modification are used for the inter-device communication after thepredetermined timing.

(2)

The communication control device according to (1), wherein thenotification unit gives notification of the radio resources availablefor the inter-device communication in system information of the cell.

(3)

The communication control device according to (1), wherein thenotification unit gives notification of the radio resources availablefor the inter-device communication through signaling to an individualterminal device.

(4)

The communication control device according to any one of (1) to (3),wherein the decision unit decides the radio resources available for theinter-device communication based on information regarding specific radioresources used by a terminal device in an idle mode of radio resourcecontrol.

(5)

The communication control device according to (4), wherein the decisionunit decides any radio resources excluding the specific radio resourcesas the radio resources available for the inter-device communication.

(6)

The communication control device according to (5), wherein the decisionunit decides radio resources of any subframe not including the specificradio resources as the radio resources available for the inter-devicecommunication.

(7)

The communication control device according to any one of (4) to (6),wherein the specific radio resources include radio resources for paging.

(8)

The communication control device according to (7), wherein the radioresources for the paging are radio resources used for paging in regardto a terminal device performing the inter-device communication.

(9)

The communication control device according to any one of (4) to (8),wherein the specific radio resources include radio resources used in arandom access procedure for transition to a connection mode of the radioresource control.

(10)

The communication control device according to (9), wherein the radioresources used in the random access procedure are radio resources of aphysical random access channel.

(11)

The communication control device according to (9), wherein the radioresources used in the random access procedure are radio resourcesselected in advance as the radio resources used in the random accessprocedure by a terminal device performing the inter-devicecommunication.

(12)

The communication control device according to any one of (1) to (11),

wherein the decision unit decides the radio resources available for theinter-device communication for each group of the inter-devicecommunication, and

wherein the notification unit gives notification of the radio resourcesdecided for each group of the inter-device communication.

(13)

The communication control device according to (12), wherein the decisionunit decides the radio resources available for the inter-devicecommunication in a manner that the radio resources available for theinter-device communication do not overlap between the groups of theinter-device communication.

(14)

The communication control device according to (13), wherein the decisionunit decides the radio resources available for the inter-devicecommunication in a manner that the radio resources available for theinter-device communication do not overlap between a first group of theinter-device communication and a second group of the inter-devicecommunication located near the first group.

(15)

The communication control device according to (2), wherein thenotification unit gives notification of the modification of the radioresources available for the inter-device communication as modificationof the system information through paging.

(16)

The communication control device according to (2), wherein thenotification unit gives notification of the modification of the radioresources available for the inter-device communication as modificationdifferent from modification of the system information through paging andrefrains from giving the notification of the modification of the radioresources as the modification of the system information through thepaging.

(17)

The communication control device according to any one of (1) to (16),wherein the radio resources available for the inter-device communicationare used for the inter-device communication by a terminal device in anidle mode of radio resource control and refrain from being used for theinter-device communication by a terminal device in a connection mode ofthe radio resource control.

(18)

A communication control method including:

deciding radio resources available for inter-device communication withina cell;

notifying a terminal device located within the cell of the radioresources; and

when the radio resources are modified, giving notification ofmodification of the radio resources through paging,

wherein, when the radio resources are modified, the radio resourcesbefore the modification refrain from being used for the inter-devicecommunication after a predetermined timing and the radio resources afterthe modification are used for the inter-device communication after thepredetermined timing.

(19)

A terminal device including:

a resource recognition unit configured to recognize radio resourcesavailable for inter-device communication within a cell when the radioresources are decided and notification thereof is given;

a control unit configured to control the inter-device communication in amanner that the recognized radio resources are used for the inter-devicecommunication; and

a modification recognition unit configured to recognize modification ofthe radio resources when the radio resources are modified andnotification of the modification of the radio resources is given throughpaging,

wherein, when the radio resources are modified, the control unitcontrols the inter-device communication in a manner that the radioresources before the modification refrain from being used for theinter-device communication after a predetermined timing and the radioresources after the modification are used for the inter-devicecommunication after the predetermined timing.

(20)

A program causing a computer to function as:

a resource recognition unit configured to recognize radio resourcesavailable for inter-device communication within a cell when the radioresources are decided and notification thereof is given;

a control unit configured to control the inter-device communication in amanner that the recognized radio resources are used for the inter-devicecommunication; and

a modification recognition unit configured to recognize modification ofthe radio resources when the radio resources are modified andnotification of the modification of the radio resources is given throughpaging,

wherein, when the radio resources are modified, the control unitcontrols the inter-device communication in a manner that the radioresources before the modification refrain from being used for theinter-device communication after a predetermined timing and the radioresources after the modification are used for the inter-devicecommunication after the predetermined timing.

REFERENCE SIGNS LIST

-   1 radio communication system-   10 cell-   100 base station-   110 antenna unit-   120 radio communication unit-   130 network communication unit-   140 storage unit-   150 control unit-   151 D2D resource decision unit-   153 D2D resource notification unit-   155 D2D resource modification notification unit-   200 terminal device-   210 antenna unit-   220 radio communication unit-   230 storage unit-   240 control unit-   241 D2D resource recognition unit-   243 D2D resource modification recognition unit-   245 D2D communication control unit

The invention claimed is:
 1. A communication control device comprising:circuitry configured to identify radio resources available forinter-device communication within a cell, the identified radio resourcesbeing assigned to a group of terminal devices for D2D communication inan idle mode, the identified radio resources being selected among radioresources available for communication in the idle mode and beingdifferent than radio resources used for a random access procedure in theidle mode; and notify a terminal device of the group of terminal devicesand located within the cell of the radio resources, wherein, when theradio resources are modified, the circuitry notifies the terminal deviceof modification of the radio resources through a paging messageincluding a flag indicating that modified radio resources will bedescribed in a subsequent message, the flag being used for indicatingmodified radio resources for the group of terminal devices and beingused for the random access procedure, and wherein, when the radioresources are modified, the radio resources before the modificationrefrain from being used for the inter-device communication after apredetermined timing and the radio resources after the modification areused for the inter-device communication after the predetermined timing.2. The communication control device according to claim 1, wherein thecircuitry gives notification of the radio resources available for theinter-device communication in system information of the cell.
 3. Thecommunication control device according to claim 1, wherein the circuitrygives notification of the radio resources available for the inter-devicecommunication through signaling to an individual terminal device.
 4. Thecommunication control device according to claim 1, wherein the circuitryidentifies the radio resources available for the inter-devicecommunication based on information regarding specific radio resourcesused by a terminal device in an idle mode of radio resource control. 5.The communication control device according to claim 4, wherein thecircuitry identifies any radio resources excluding the specific radioresources as the radio resources available for the inter-devicecommunication.
 6. The communication control device according to claim 5,wherein the circuitry identifies radio resources of any subframe notincluding the specific radio resources as the radio resources availablefor the inter-device communication.
 7. The communication control deviceaccording to claim 4, wherein the specific radio resources include radioresources for paging.
 8. The communication control device according toclaim 7, wherein the radio resources for the paging are radio resourcesused for paging in regard to a terminal device performing theinter-device communication.
 9. The communication control deviceaccording to claim 4, wherein the specific radio resources include radioresources used in a random access procedure for transition to aconnection mode of the radio resource control.
 10. The communicationcontrol device according to claim 9, wherein the radio resources used inthe random access procedure are radio resources of a physical randomaccess channel.
 11. The communication control device according to claim9, wherein the radio resources used in the random access procedure areradio resources selected in advance as the radio resources used in therandom access procedure by a terminal device performing the inter-devicecommunication.
 12. The communication control device according to claim1, wherein the circuitry identifies the radio resources available forthe inter-device communication for each group of the inter-devicecommunication, and wherein the circuitry gives notification of the radioresources identified for each group of the inter-device communication.13. The communication control device according to claim 12, wherein thecircuitry identifies the radio resources available for the inter-devicecommunication in a manner that the radio resources available for theinter-device communication do not overlap between the groups of theinter-device communication.
 14. The communication control deviceaccording to claim 13, wherein the circuitry identifies the radioresources available for the inter-device communication in a manner thatthe radio resources available for the inter-device communication do notoverlap between a first group of the inter-device communication and asecond group of the inter-device communication located near the firstgroup.
 15. The communication control device according to claim 2,wherein the circuitry gives notification of the modification of theradio resources available for the inter-device communication asmodification of the system information through paging.
 16. Thecommunication control device according to claim 2, wherein the circuitrygives notification of the modification of the radio resources availablefor the inter-device communication as modification different frommodification of the system information through paging and refrains fromgiving the notification of the modification of the radio resources asthe modification of the system information through the paging.
 17. Thecommunication control device according to claim 1, wherein the radioresources available for the inter-device communication are used for theinter-device communication by a terminal device in an idle mode of radioresource control and refrain from being used for the inter-devicecommunication by a terminal device in a connection mode of the radioresource control.
 18. A communication control method comprising:identifying radio resources available for inter-device communicationwithin a cell, the identified radio resources being assigned to a groupof terminal devices for D2D communication in an idle mode, theidentified radio resources being selected among radio resourcesavailable for communication in the idle mode and being different thanradio resources used for a random access procedure in the idle mode;notifying a terminal device of the group of terminal devices and locatedwithin the cell of the radio resources; and when the radio resources aremodified, notifying the terminal device of modification of the radioresources through a paging message including a flag indicating thatmodified radio resources will be described in a subsequent message, theflag being used for indicating modified radio resources for the group ofterminal devices and being used for the random access procedure, andwherein, when the radio resources are modified, the radio resourcesbefore the modification refrain from being used for the inter-devicecommunication after a predetermined timing and the radio resources afterthe modification are used for the inter-device communication after thepredetermined timing.
 19. A terminal device comprising: circuitryconfigured to recognize radio resources available for inter-devicecommunication within a cell when the radio resources are identified andnotification thereof is given, the radio resources being assigned to agroup of terminal devices including the terminal device for D2Dcommunication in an idle mode, the radio resources being selected amongradio resources available for communication in the idle mode and beingdifferent than radio resources used for a random access procedure in theidle mode; control the inter-device communication in a manner that therecognized radio resources are used for the inter-device communication;and recognize modification of the radio resources when the radioresources are modified and notification of the modification of the radioresources is given through a paging message including a flag indicatingthat modified radio resources will be described in a subsequent message,the flag being used for indicating modified radio resources for thegroup of terminal devices and being used for the random accessprocedure, and wherein, when the radio resources are modified, thecircuitry controls the inter-device communication in a manner that theradio resources before the modification refrain from being used for theinter-device communication after a predetermined timing and the radioresources after the modification are used for the inter-devicecommunication after the predetermined timing.
 20. A non-transitorycomputer-readable storage medium storing instructions thereon, which,when executed by a terminal device, cause the terminal device perform amethod, the method comprising: recognizing radio resources available forinter-device communication within a cell when the radio resources areidentified and notification thereof is given, the radio resources beingassigned to a group of terminal devices including the terminal devicefor D2D communication in an idle mode, the radio resources beingselected among radio resources available for communication in the idlemode and being different than radio resources used for a random accessprocedure in the idle mode; controlling the inter-device communicationin a manner that the recognized radio resources are used for theinter-device communication; and recognizing modification of the radioresources when the radio resources are modified and notification of themodification of the radio resources is given through a paging messageincluding a flag indicating that modified radio resources will bedescribed in a subsequent message, the flag being used for indicatingmodified radio resources for the group of terminal devices and beingused for the random access procedure, and wherein, when the radioresources are modified, the controlling controls the inter-devicecommunication in a manner that the radio resources before themodification refrain from being used for the inter-device communicationafter a predetermined timing and the radio resources after themodification are used for the inter-device communication after thepredetermined timing.
 21. An electronic device comprising: circuitryconfigured to receive radio resource information for Device-to-Device(D2D) communication, the radio resources indicated by the radio resourceinformation being assigned to a group of electronic devices includingthe electronic device for D2D communication in an idle mode, the radioresources being selected among radio resources available forcommunication in the idle mode and being different than radio resourcesused for a random access procedure in the idle mode; perform D2Dcommunication with another electronic device in the idle mode; obtainmodified radio resource information for the D2D communication afterreceiving, in the idle mode, a paging message including a flagindicating that the modified radio resources will be described in asubsequent message, the flag being used for indicating modified radioresources for the group of electronic devices and being used for therandom access procedure; and communicate with another electronicapparatus via the D2D communication using resources indicated by themodified radio resource information.